1. Field of the Invention
This invention relates to a method for fabricating a thin film magnetic head and a wafer structure.
2. Related Art Statement
A complete thin film magnetic head is obtained by polishing a given surface of a thin film magnetic head assembly which is fabricated on a given substrate to form an air bearing surface (ABS). In a thin film magnetic head assembly including a magnetoresistive effective type reading element, the polishing process is carried out so that the MR height is constant (the MR height is defined). Herein, the MR height is a processed length of the assembly from the end surface of the thin film magnetic head assembly.
In this case, an electrical lap-guiding element (often called as “lap-guiding element”, hereinafter) is fabricated on the substrate where the thin film magnetic head assembly is fabricated, and thus, the polishing process is carried out with monitoring the size of the MR height through the electrical changes of the lap-guiding element.
FIG. 1 is a plan view showing a wafer structure in which thin film head assemblies and lap-guiding elements are fabricated on a single wafer as a substrate, and FIG. 2 is a cross sectional view of a portion of the wafer structure of FIG. 1, taken on line X—X. In FIG. 1, for simplicity, the thin film head assemblies and the lap-guiding elements are fabricated on the trailing surface 1A of the wafer 1 in a line by turns. In FIGS. 1 and 2, for clarifying the characteristics of the present invention, the detail structure of the wafer structure is different from a real one.
A thin film magnetic head assembly 10 includes element pads 2a; 2b and 3a; 3b which are exposed on the trailing surface 1A of the wafer 1. The element pads 2a and 2b are electrically connected to a MR element of the thin film magnetic head assembly 10 via leading wires 4a and 4b. The element pads 3a and 3b are electrically connected to a writing element 6 of the thin film magnetic head assembly 10 via leading wires 5a and 5b. 
A lap-guiding element 20 includes circuit pads 21a and 21b, and is connected to a resistive film 24 made of the same material as that of the MR film to construct the MR element via leading wires 22a and 22b. The polishing process is carried out from the end surface 1B of the wafer 1. The polishing degree of the MR element is checked by the change in resistance of the resistive film 24, and thus, the MR height is monitored indirectly.
Practically, a protective layer 15 is formed on the trailing surface 1A so as to cover the thin film head assemblies and lap-guiding elements.
Therefore, as shown in FIG. 2, the circuit bump 27 is provided so as to penetrate the protective layer 15, and electrically connected to the leading wire 22b and the circuit pad 21b. Then, the change in resistance of the resistive film 24 is monitored through the circuit pad 21b, and the processing degree of the ABS, that is, the MR height is indirectly controlled.
Also, an element bump 7 is provided so as to penetrate the protective layer 15, and electrically connected to the leading wire 4a and the element pad 2a. The element bump 7 is electrically connected to the MR element via the leading wire 4a. 
With the recent development of high recording density and small cutting space, the distance between a thin film magnetic head assembly and an electrical circuit is narrowed on a substrate on which the thin film head assembly and the electrical circuit are disposed. In FIG. 2, therefore, the distance between the circuit bump 27 and the element bump 7 is also narrowed, for example.
In this case, however, the short-circuit between the thin film magnetic head assembly 10 and the lap-guiding element 20 may occur. In addition, some cracks and chirping may be created between the circuit bump 27 and the element bump 7, and thus, some defects may be created in the resulting thin film magnetic head.